Studies of chemical disposition are designed to provide both applied knowledge of the fate of chemicals in the intact animal in support of toxicity studies conducted by the National Toxicology Program (NTP) and basic knowledge of mechanisms of chemical toxicity. Recent studies have addressed the fate and potential toxicity of luminol (5-amino-2,3- dihydrophthalazine-1,4-dione) the most widely used member of the phthalazine dione class. Human exposure to luminol occurs during its use as a laboratory reagent and in forensic toxicology in which it is sprayed over the general area in which a crime was committed to detect blood or semen. Knowledge of the fate and toxicity of luminol is of interest because of its significant potential for human exposure. Results of these studies indicate that luminol is readily absorbed from the gastrointestinal tract and rapidly metabolized and excreted. Metabolism is near complete to two major metabolites that are excreted primarily in urine. One metabolite is stable and has been determined to be an N-glucuronide. The second metabolite is unstable, but has been determined to be an N-sulfonamide conjugate of the parent molecule. Very little of the parent molecule is excreted intact and neither luminol nor it metabolites accumulate in tissues. These studies have also determined that luminol is very poorly absorbed from skin. On consideration of the facts the parent molecule and its metabolites have little potential for bioacumulation, toxicity or carcinogenicty and the parent is minimally absorbed following the anticipated route of exposure, dermal, luminol has been recommended for no further study by the NTP. - chemical disposition, metabolism, luminol